A recent **study** published in Nature Communications questions the theory that most **male mammals** are larger than females, an idea supported since the times of **Charles Darwin**.
Severine Hex, a researcher at **Princeton University**, explains that Darwin and other scientists probably observed larger and more striking taxa, such as **carnivores and primates**, where males are physically impressive and compete for smaller females.
However, when comparing the **body masses** of male and female mammals in 429 species, it was found that in many of them, both sexes are similar in size, like lemurs, horses, zebras, and tenrecs.
Sexual Dimorphism in Mammals
In 45% of the species analyzed, males were larger, while in 16% females were larger, and in the remaining 39%, both sexes were the same size.
Examples of **exaggerated sexual dimorphism** include large carnivores and some species of primates and ungulates. Biases in scientific literature may have contributed to the **misconception** that males are generally larger.
Reasons for Size and Differences
Researchers suggest that selective pressures determine size in different species. In many species of **invertebrates and fish**, larger females can carry more eggs, increasing their fecundity.
However, size is not always advantageous, especially in high-temperature environments where it hinders thermoregulation.
Body mass differences also depend on competition for mates and parental investment in offspring. For example, male **lions and baboons** physically compete for mates, while relatively larger rabbits often have multiple litters per season.
Implications for Research
The findings highlight the need for more research on the **biology of females** in all species. It is crucial to reassess hypotheses and theories as knowledge of the natural world improves.
Attention to small and less studied species is essential to continue developing our understanding.
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